<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>css-画心形</title>
<style type="text/css">
.heart{
    position:relative;
    width:200px;
    height:200px;
    background-color: orange;
    margin:100px auto;
    -webkit-transform: rotate(45deg);
    moz-transform: rotate(45deg);
    -o-transform: rotate(45deg);
    -ms-transform: rotate(45deg);
    transform: rotate(45deg);
}
.heart:before,.heart:after{
    position:absolute;
    content:'';
    width:200px;
    height:200px;
    display:block;
    border-radius:50%;
    background-color: orange;
}
.heart:before{
    left:-100px;
    bottom:0;
}
.heart:after{
    top:-100px;
    right:0;
}
</style>

</head>
<body>
<div class="heart"></div>
</body>
</html>